Short wave oscillator



Dec. 9, 1941. BOERSCH 2,265,796

SHORT WAVE 05 C ILLATOR Filed Dec. 2, 1939 11W & LN TOR. HANS BOERS CH ATTORNEY.

Patented Dec. 9, 1941 UNIT kil SHORT WAVE OSCILLATOR Hans Boer-sch,Berlin, Germany, assignor to General Electric Company, Schenectady, N.Y., a

corporation of New York Application December 2, 1939, Serial No. 307,218In Germany December 13, 1 938 6 Claims.

The invention is concerned with the generation of electric oscillationsof a wavelength on the order of magnitude of millimeters or centimeters.It is known that waves having the foregoing lengths may be produced bymeans of magnetrons or retarding field (electron oscillation) tubes.However, a limitation is imposed upon the production of waves by thesaid dscillator means because of the dimensions of the electrode systemof such oscillators. Fjor instance, in a practical magnetron tube fittedwith a solid (unsplit) anode, the anode cylinder is of a diameter of 1mm. in order that the tube may be enabled to generate an electricoscillation of the order of 1 centimeter. However, to make an electrodesystem of this size, not to speak of still further diminished sizes, isattended with extremely great technical difficulties.

It is known in the art that there are dipole substances which willselectively absorb waves inside the range of millimeters andcentimeters. Substances of the said sort, for instance, are water,alcohol, and ammonia. Selective absorption seems to be predicated uponthe fact that the dipoles (dipole molecules) of the substance, in turn,are excited by electric oscillations to experience oscillations, thisresulting in a sort of anomalous dispersion; that is, the said selectiveabsorption of the electric oscillations within the range or band ofmillimeter and centimeter waves.

The object of the invention is an arrangement obviating the difiicultiesabove enumerated and which is adapted to the production ofultrashort-wave oscillations and which comprises a dipole substanceexhibiting selective absorption in the range of millimeter and decimeterwaves, more particularly ammonia, the dipoles of which are capable ofgenerating ultra-short oscillations by the action of oscillations whichcorrespond to the said absorption band.

The invention shall now be explained in more detail by reference to theappended drawing in which Figs. 1 and 2 show two embodiments of theinvention, given by way of example only.

Referring to Fig. l of the drawing, l denotes a spherical vessel whichis filled with ammonia vapors. Confined inside the vessel 1 are twoplate-shaped electrodes 2 and 3 placed so as to face each other. Insteadof plates, also grid or grate-shaped electrodes could be used. Themeshes of such reticulate electrodes should surpass and exceed thelength of the waves to be generated. To these electrodes may be fed byway of the leads 5 and 5 an RF electrical field from source I5, thefrequency being of an order of magnitude less than the frequency to begenerated. As an illustration, if the frequency to be generated by thedipole substance is to be 1 cm., then the frequency of the source l5might be 10 cm. By the action or the said alternating electrical fieldcross the electrodes 2 and 3, the dipoles of the gas are excited tooscillate with the result that electrical waves whose wavelength is ofthe order of millimeters or centimeters are produced. In order toprevent these waves from being absorbed by the wall or shell I, it isexpedient to use for the said wall or shell a substance exhibiting lowabsorptivity, a synthetic resin such as Trolitul, for instance.

Another exemplified embodiment of an arrangement according to thepresent invention is represented in Fig. 2. It distinguishes itself fromthe one of Fig. 1 only by the shape of the vessel in which are mountedthe electrodes II and I2 between which the electrical field is set upand which have the supply leads 9 and Ill. The vessel is indicated at 6.It may consist of metal, the leads 9 and i ll being introduced thereinwhile being insulated therefrom. The vessel has the form of a paraboloidof rotation. The inside thereof is lined with a reflecting coat or layer8. The vessel is shut by means of a window which is permeable toelectrical waves. Trolitul may here be used for the window. Theelectrical oscillations produced in the ammonia vapors filling thevessel 6 are reflected from the layer 8 and reach the outside throughthe said window I.

For the excitation of the dipole oscillations recourse could be had alsoto means and auxiliaries other than electrical fields. For instance, itmay be expedient to subject the dipole substance which serves for thegeneration of ultra 'short oscillations to mechanical vibrations; say

ultra-acoustic (suprasonic) waves.

What is claimed is:

An ultra high frequency generator for radio waves of the order of a fewmillimeters in wavelength, comprising an enclosed vessel containing agaseous substance having dipolar molecules which exhibit selectiveabsorption in a desired frequency range, and means for exciting saidmolecules whereby electromagnetic waves in the desired frequency rangeare generated.

2. An ultra high frequency generator for radio waves of the order of afew millimeters in wavelength, comprising an enclosed vessel containinga gaseous substance having dipolar molecules which exhibit selectiveabsorption in a desired frequency range, and means for applying a radiotrical waves of the order of centimeters and less.

4. An ultra high frequency generator for radio waves of the order of afew millimeters in wavelength, comprising an enclosed vessel containinga fluid substance composed of dipolar nonmetallic molecules whichexhibit selective absorption in a desired frequency range, and means forexciting said molecules whereby electromagnetic waves in the desiredfrequency range are generated.

5. An ultra high frequency generator for radio waves of the order of afew millimeters in wavelength comprising an enclosed vessel containing afluid substance composed of dipolar molecules which exhibit selectiveabsorption in a desired frequency range, and means for forcefullyexciting said molecules whereby electromagnetic waves in the desiredfrequency range are generated.

6. An ultra high frequency generator for radio waves of the order of afew millimeters in wavelength, comprising an enclosed vessel containingan alcoholic substance composed of dipolar non-metallic molecules whichexhibit selective absorption in a desired frequency range, and means forexciting said molecules whereby electromagnetic waves in the desiredfrequency range are generated.

HANS BOERSCH.

